In a general wireless communication network such as cellular phone service, a number of base stations are installed so that communication is performed at any location. The base stations include an outdoor base station and a micro-mini base station. The outdoor base station covers a communication area (macrocell) of a radius of approximately several kilometers and is installed on a roof of a building or a steel tower. The micro-mini base station covers a communication area (femtocell) of a radius of approximately several tens of meters and is installed in a small office or an ordinary house. The outdoor base station is also referred to as a “macro base station”. The micro-mini base station is also referred to as a “femto base station” (hereinafter also referred to as “femto”), a “femtocell base station”, a “femtocell micro base station”, or a “femtocell micro wireless base station”.
Installation locations of base stations in a wireless communication network are determined so that optimum throughputs are obtained. Therefore, the base stations are assumed not to be displaced after once being installed. If the base stations are arbitrarily displaced, there may arise problems in that interference of radio waves is generated, throughputs are degraded, and connection is not established. Furthermore, in emergency situations, positional information which has been registered is to be transmitted to an emergency contact party such as a police station, a fire station, or the like. However, if the base stations are arbitrarily displaced, positional information transmitted to the emergency contact party does not match an actual location. The femto base stations are portable devices. However, in some areas, femto base stations are banned from being displaced pursuant to laws and regulations. For example, in Japan, displacement of a femto base station without permission may be punishable according to the Radio Act, the Electricity Business Act, or the like. Accordingly, a technique of managing installation locations of micro-mini base stations is demanded.
Therefore, the following system (System-1) has been proposed. A micro-mini base station receives, from a communication device such as a cellular phone positioned in a radio wave zone of the micro-mini base station, positional information obtained by the communication device from a GPS (global positioning system) satellite, and transmits the positional information to a management apparatus of the micro-mini base station.
Furthermore, the following system (System-2) has also been proposed. A portable micro base station which relays wireless communication of wireless communication terminals to a mobile communication network monitors states of radio waves from other base stations installed near the micro base station. In System-2, the micro base station which monitors the states of the radio waves of the other base stations installed near the micro base station detects changes in the states of the radio waves of the other base stations to detect changes in the positional relationships between the micro base station and the other base stations on the basis of the detected changes in the states of the radio waves. Then the micro base station estimates change of an installation location of the micro base station on the basis of the detected changes in the positional relationships.
Japanese Laid-open Patent Publication No. 2009-232286 and Japanese Laid-open Patent Publication No. 2010-28729 disclose related techniques.
System-1 is designed on the assumption that a wireless device such as a cellular phone existing in the radio wave zone of the micro-mini base station normally functions as a GPS receiver. Therefore, in System-1, if only wireless devices which have no function of receiving a signal from a GPS satellite exist in the radio wave zone, displacement of the micro-mini base station is not detected. In addition, if only wireless devices which do not normally function as a GPS receiver since the wireless devices exist in an environment in which the wireless devices are not allowed to obtain desired reception quality of a reception signal received from the GPS satellite exist in the radio wave zone, displacement of the micro-mini base station is not detected.
In System-2, there arises a problem in that, when the micro-mini base station detects radio waves of other base stations installed near the micro-mini base station, service of the micro-mini base station is stopped. Specifically, while the micro-mini base station detects the radio waves of the other base stations near the micro-mini base station, a process regarding wireless communication between the micro-mini base station and wireless devices such as cellular phones existing in the radio wave zone of the micro-mini base station is interrupted or stopped in the micro-mini base station.